With the latest AppScale release (3.4), we will default all new deployments and installation to Ubuntu 16.04 LTS (Xenial). Published AppScale images are based on Long Term Support images to ensure stability and easy upgradability. Our choice

of Server-based LTS images is dictated by our desire to provide a stable production-ready environment to run App Engine applications, ensuring that security patches, and long-term stability fits well with any application lifecycle.

We started to support Xenial builds with the start of AppScale 3 series, and now after a few releases of stable builds and comprehensive testing, it is time to officially switch our default builds. Functionally there are no visible changes that an App Engine application will observe, so any deployment can be migrated to Xenial with no adverse effect.

Why Ubuntu 16.04 for AppScale?

At the level below applications, Xenial brings a welcome refresh on our dependencies, with some fixes that will eventually allow us to remove workarounds (once we remove builds for the older LTS versions), and make our builds leaner and faster. One of the big changes is the switch to systemd. This change is handled by AppScale deployment code, but if you have custom scripts, you will have to port them to the new init system.

Our CI/QA builds are still testing the previous LTS (Trusty), so any running deployment can still be manually updated in place, instead of migrating to the newer LTS. Although moving to the latest LTS is recommended, it is not required at this time. Precise, the very old LTS, has been removed from our daily QA cycle: if you happen to still run on Precise, we urge you to upgrade to Xenial. AppScale will still build and run on Precise, but we won’t QA that consistently.

Why AppScale?

The App Engine/AppScale model guarantees a stable, integrated, performant, and scalable environment for your application, and AppScale ensures correct functioning of your application on all of the above LTS versions and all supported infrastructures. While the decision of when to move to the latest LTS and on which cloud to run is now fully decoupled from the development of the application itself, we always recommend that you are running on the latest version of AppScale, with all security updates applied.